There are many different ways of training plants. To train a plant to develop four branches just cut off all branches except for the top four. To keep them out of each other's way use stakes or supports for each branch. If new branches start to grow, then trim them off the plant.
To develop multiple branching you can twist the plant down so what was the top of the plant no longer is higher than other branches. Then some of the lower branches will start growing vertically and producing their own side branches. The more traditional way to promote more branching is to pinch the top of the plant. When that happens, the top two branches are no longer inhibited from growing by chemical inhibitors produced by the top. After they grow a bit, the two new tops can be pruned and their lower branches will also grow. Before you know it, you have a bush.
Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA. You can also email Ed at AskEd@cannabisculture.com, and send queries via his websites at www.ask-ed.net. All featured questions will be rewarded with a copy of Ed's new book, Best of Ask Ed: Your Marijuana Questions Answered. Sorry, Ed cannot send personal replies to your questions.